[clang] [clang][HLSL] Add sign intrinsic part 3 (PR #101989)

[Farzon Lotfi via cfe-commits]

farzonl wrote:

> @farzonl This PR requires the SPIRV part (#101987) to be merged.
I haven't signed off on that one because I wanted input from others. I'll ping some folks.
If the pr is still sitting we can make a small change in this pr that will unbloc it. Add the spirv intrinsic to this pr that should be enough to prevent a compile error.

https://github.com/llvm/llvm-project/pull/101989